In a video game field, actions of an object (a character) of walking, running, etc., in a virtual three-dimensional space are reproduced using motion data (e.g., see Patent Literature 1). The motion data includes data for changing a posture of a character across a plurality of frames (from a first frame to an nth frame) of a video image. This information includes position information of joints which are components of the character.
The frames from the first frame to the nth frame correspond to, for example, the number of reproduction frames that form a single unit of action. In walking, for example, an action of putting the right foot and the left foot alternately forward one by one is a single unit of action. Therefore, a single unit of action of a character is reproduced by generating the character in postures in accordance with data in an order of the frames from the first frame to the nth frame. Regarding the motion data, a plurality of sets of motion data are prepared as game data for a plurality of actions.
In video games, sound effects, etc., are output in response to the actions of the character. For example, with the walking action of the character, a sound effect representing sound of footsteps is output each time the foot of the character touches the ground. The sound effect is output in accordance with sequence data associated with the motion data. As in the motion data, the sequence data for each frame is prepared in time series for the frames from the first frame to the nth frame. The sequence data is, for example, data for identifying timing at which the above-described sound effect is to be produced (a production frame). Production timing is set in, for example, an appropriate frame while a manufacturer of the video game plays the actions of the character.
In some recent video games, a character is made to perform an action in which two sets of motion data are blended. For example, motion data for walk and motion data for run are blended to cause the character to jog, which is an action between walk and run. The character is caused to jog when, for example, position information of joints included in frames of the motion data for walk and frames of the motion data for run that are associated with each other are blended in accordance with a blend rate. Also, a jogging action close to walking (or running) can be expressed in accordance with the blend rate.